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Theoretical insight on catalytic activity of bimetallic gold catalystsтезисы доклада
- Авторы: Pichugina D.A., Mukhamedzyanova D.F., Beletskaya A.V., Ratmanova N.K., Snyga J.G., Nikolaev S.A.
- Сборник: IX International Conference Mechanisms of Catalytic Reactions. October 22-25, 2012 StPetersburg, Russia
- Тезисы
- Год издания: 2012
- Место издания: Novosibirsk 2012 Новосибирск
- Первая страница: 32
- Последняя страница: 32
- Аннотация: The study of catalytic properties and structure of bimetallic clusters contained gold and platinum group atoms is the promising field. Here we present the new results of quantum-chemical investigation of Ni and Pd influence on active sites formation in small gold clusters. Simulation of ligand effects and ensemble effects has been performed in AunNi and AunPd bimetallic systems. The possible reaction pathways of H2O2 formation (reaction 1) and hydrocarbons isomerization (reaction 2) on Au7Pd and Au3Ni have been studied in details and compared with those on the pure gold clusters Au8 and Au4. Scalar-relativistic DFT with modified Dirac-Coloumb-Breit Hamiltonian and the nonempirical local PBE functional have been applied. In some cases plane-wave basis set and ultrasoft pseudopotentials in periodic boundary conditions have been used. Firstly, the models of bimetallic catalyst have been selected. The calculation involved the optimization of AunX structures (X=Ni, Pd, n=2÷7) in the various spin multiplicities, analyses of average Au-X and Au-Au distances, atomic charge (AC), molecular orbitals (MO) as well as cluster’s binding energies and ΔGT in cluster’s formation process. It was obtained that (i) in AunNi the distances increased versus Aun+1, (ii) binding energies per atom increased when the n increased, (iii) the sole role of Au atoms in clusters is to shift the d states of the Pd, (iv) Pd and Ni influences significantly the charge redistribution in AunX. From all bimetallic systems Au3Ni and Au7Pd have been chosen for further investigation. Based on AC and MO analysis of bimetallic clusters it is supposed that Auδ+ site is the most active in unsaturated hydrocarbons adsorption, while Auδ- is active in oxygen adsorption. The simulation of mechanism of the reactions 1 and 2 confirmed our assumption.
- Добавил в систему: Пичугина Дарья Александровна